Phosphorus fractions in argentine soils of different pedogenesis

Abstract

The distribution of phosphorus (P) in different organic and inorganic fractions was examined in five Argentinean soils of different pedogenesis. Soils were sequentially extracted to determine resin‐P, bicarbonate‐P, and hydroxide‐P fractions. Inorganic P (IP) predominated in all soils, specially moderately resistant IP (MRIP) in Entisol, Vertisol, and Ultisol. Both MRIP and labile IP (LIP) were important in Mollisol. Organic P (OP) was at a lower concentration in all soils and moderately resistant OP (MROP) was highest in all soils, except for the Mollisol. In intermediate evolution soils, labile P (LP) was very important, Mollisol had the highest value of LP%, and the lowest was for the Ultisol, demonstrating greater dynamics of P fractions in the Mollisol, soils of high productivity in the Pampean Prairie.     

中国长江中下游地区浅水湖泊沉积物有机磷研究

Thirteen sediment core samples （0 10 cm） were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus （P） fractions in the sediments of the shallow lakes in the area. The organic P fractions in the sediments were in the order of moderately labile organic P （MLOP） 〉 moderately resistant organic P （MROP） 〉 highly resistant organic P （HROP） 〉 labile organic P （LOP）, with average proportional ratios of 13.2：2.8：1.3：1.0. LOP, MLOP, and MROP were significantly related to the contents of total organic carbon （TOC）, water-soluble P （WSP）, algal-available P （AAP）, NaHCO3-extractable P （Olsen-P）, total P （TP）, organic P （OP）, and inorganic P （IP）. However, HROP was significantly related to OP and weakly correlated with TOC, WSP, AAP, Olsen-P, TP or IP. This suggested that organic P, especially LOP and MLOP in sediments, deserved even greater attention than IP in regards to lake eutrophication. In terms of organic P, sediments were more hazardous than soils in lake eutrophication. Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment, LOP and MLOP were higher in the heavily polluted sediment, which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.     

Availability of Organic and Inorganic Phosphorus Fractions to Wheat in Toposequences of Calcareous Soils

Abstract

Information on the availability of different soil phosphorus (P) forms is useful for crop production. Phosphorus contents of 12 Iranian calcareous soils from upper‐, mid‐, and lower‐slope positions of two arid and two semiarid toposequences were fractionated to various organic and inorganic pools, and correlations of the P fractions with wheat responses were investigated. Among the inorganic P (IP) fractions, apatite type (Ca₁₀‐P) and dicalcium phosphate equivalents (Ca₂‐P) possessed the highest and the lowest amounts of P reserve in the soils, respectively. On average, about 20% of the total P was found in organic form (OP), of which 32% was labile (LOP), 51% was moderately labile (MLOP), and 17% was nonlabile (NLOP). The amounts of the soil P fractions were considerably influenced by the positions of the soils on the landscapes. The maximum contents of soil IP, Ca₂‐P, Fe‐P (iron‐bound P), and Ca₁₀‐P were observed in the lower‐slope positions. The amount of soil available [0.5 M sodium bicarbonate (NaHCO₃) extractable] P was significantly correlated with Ca₂P (r=0.895), Fe‐P (r=0.760), and Occl‐P (iron‐occluded P) (r=0.897). Direct correlation studies, however, showed that wheat shoot dry‐matter yield (DMY) was significantly affected by the amounts of Ca₂‐P, Fe‐P, OP, LOP, and MLOP fractions both at early (4 weeks) and late (10 weeks) stages of growth. All organic and inorganic P fractions, except Al‐P (aluminum‐bound P), Ca₈‐P (octacalcium phosphate equivalents), and NLOP, also showed significant relations to the amount and/or concentration of P in wheat tissues at 4 and 10 weeks after sowing. Among the measured soil properties, the amount of organic carbon was the most affecting factor on the size of the P fractions.     

连续施肥对土壤磷钾组分变化的影响

以 10年肥料定位试验土壤为材料 ,研究了连续施肥对 3种土壤磷钾组分含量的影响。结果表明 ,连续施用NPK化肥、化肥基础上增施有机肥 ,均可提高土壤有机磷总量、无机磷总量、全钾含量及其它各组分 (形态 )的含量。有机磷总量平均分别提高 0.34倍和 1.08倍 ,其中AOP提高 1.71倍和 2.45倍 ;无机磷总量分别提高 0.40倍和 0.47倍 ,其中Ca2-P提高 6.3倍和 7.69倍 ;全钾含量提高很少 ,但水溶性钾提高 6.88倍和 11.17倍。连续 10年不施肥土壤磷钾总量及各组分含量均降低。连续施钾与不施钾 ,土壤粘粒X射线衍射图谱没有明显差异 ,但不施K肥土壤粘粒 ( 2 m)全钾含量降低     

Aging effects of organic and inorganic fertilizers on phosphorus fractionation in a calcareous sandy loam soil

In most arid and semiarid soils, naturally occurring phosphorus(P) is a major yield-limiting plant nutrient. In this study, to investigate the effects of organic(OP) and inorganic P(IP) sources on P fractionation, a calcareous sandy loam alkaline soil was fertilized with OP and IP fertilizers at low(80 mg P kg~(-1) soil) and high(160 mg P kg~(-1) soil) application rates. Three combinations of OP and IP(i.e., 75% OP + 25% IP, 50% OP + 50% IP, and 25% OP + 75% IP) were applied at low and high application rates,respectively, followed by soil aging for 21 d. Soil samples were collected after 1, 2, 3, 7, and 21 d and subjected to sequential extraction to analyze soluble and exchangeable, Fe-and Al-bound, Ca-bound, and residual P fractions. The soluble and exchangeable P fraction significantly increased up to 24.3%, whereas the Ca-bound fraction decreased up to 40.7% in the soils receiving 75% OP + 25% IP and 50% OP + 50% IP, respectively, compared with the control(receiving no P fertilizer). However, the transformation of P fractions was influenced by aging time. Addition of P sources caused instant changes in different P fractions, which then tended to decline with aging time. Change in soil p H was the limiting factor in controlling P availability. At high application rate, the OP source significantly increased soil P availability compared with the IP source with soil aging. Depending on P fractionation, a proper combination of OP and IP fertilizers, as long-term slow and instant P-releasing sources for plant uptake, respectively, may be a sustainable strategy to meet crop P requirements in the arid and semiarid soils.     

Soil phosphorus mobilization in different taxonomic orders

Changes in P fractions using Hedley's sequential fractionation of organic and inorganic soil P, were studied in soils covering a wide range of developmental stages and original materials. A greenhouse experiment was performed in order to make an exhaustive P uptake by Lolium perenne and to study soil phosphorus mobilization from different fractions. Samples were obtained at 30, 60 and 90 days from sowing, with two fertilization rates added as KH₂PO₄. The exhaustion produced by plants resulted in different patterns of mobilization according to soil characteristics. For control soils the contents of inorganic labile fraction (LIP) decreased at the end of the experience in Mollisol (31%), Vertisol (24%) and Andisol (17%). The mobilization of organic P was greater for Ultisol and Andisol (77 and 75% respectively) than for the other soils. Fertilization affected mainly inorganic P, with a significant increase in contents of LIP in Entisol (46%) and moderately resistant inorganic P (MRIP) in Andisol (15%). Inorganic P/organic P relationship tended to increase during the experiment, while labile P/moderately resistant P increased in Entisol and Mollisol.     

湖南稻田土壤有机磷组分的施磷效应、季节变化及生物有效性研究

为探明施用磷肥对湖南稻田土壤有机磷组分的影响、有机磷组分的季节变化及其有效性,以湖南省5种不同母质发育的稻田土壤为供试土壤,通过盆栽试验,研究了稻田土壤有机磷组分的施磷效应、在植稻期间的动态变化及其生物有效性。结果表明,施用磷肥可以使土壤中活性有机磷得到较大的增加,而对活性有机磷、中稳性有机磷和高稳性有机磷影响较小。在施磷和不施磷条件下,土壤有机磷的变化主要是中活性有机磷,而其余3种形态有机磷在水稻生长期间几乎保持不变。不管土壤是否施用磷肥,土壤有效磷与有机磷总量总是呈极显著相关,说明土壤有机磷的确是植物可以利用的有效磷源;在早稻生长期间土壤各形态有机磷的生物有效性的大小顺序为:中活性有机磷中稳性有机磷高稳性有机磷活性有机磷;在晚稻生长期间土壤各形态有机磷的生物有效性一般随水稻生育期不同而不同。     

Effect of organic manure on organic phosphorus fractions in two paddy soils

We investigated the transformation of the organic P fractions from organic manure in two paddy soils (Ultisol, Entisol) and the influence of organic manure or cellulose on organic P under anaerobic conditions. The results obtained from the P fractionation experiment indicated that during the incubation labile and moderately labile organic P fractions increased in the Ultisol and decreased in the Entisol, which might be related to the difference in the organic matter content of both soils. Immediately after the application of organic manure, a large part of labile and moderately labile organic P supplied with the manure was transformed into moderately resistant organic P, possibly Ca- or Mg-inositol P were transformed into Fe-inositol P. During anaerobic incubation, the labile forms of organic P in the soils treated with organic manure were increased along with the incubation period in the first 4 weeks. The change in the moderately labile fraction was dramatic. It increased sharply in the first 2 weeks, then decreased, which was more pronounced in the soils treated with pig faeces. The moderately resistant fraction decreased during the whole incubation period. This indicated that under anaerobic conditions, the moderately resistant fraction can be transformed into labile and moderately labile organic P fractions, perhaps as Fe³⁺-inositol P is reduced to Fe⁺²-inositol P. Cellulose as an organic substrate had an increasing effect on organic P, especially when it was combined with inorganic P. Therefore, it is suggested that the application of inorganic P fertilizer combined with organic manure may be an effective way of protecting inorganic P against intensive sorption in soils.     

施肥对红壤稻田硫素演变及供硫能力的影响

研究了进行 15年的不同施肥结构对红壤稻田土壤硫素肥力演变和对土壤供硫能力的影响。结果表明 ,不同施肥结构明显影响土壤全硫、有机硫、无机硫和供硫潜力 (无机硫加部分有机硫 ,40℃KCl浸提 )的演变时间进程以及土壤有机硫的潜在矿化量、矿化常数和矿化半减期 ,稻草还田和有机肥施用有利于土壤硫的积累 ,提高土壤供硫能力 ;连续盆栽幼苗试验结果表明 ,作物吸硫量以稻草还田区 有机肥加化肥区 全化肥区 无肥区 ,与土壤全硫、供硫潜力及土壤硫潜在矿化量顺序一致     

Bowman-Cole土壤有机磷分组法的探讨

采用Bowman-Cole法的几种浸提剂和浸提步骤大体上可将矿化难易不同的几种有机磷化合物区分开来.采用该法所测得的土壤有机磷四种组分,其矿化速率有随土壤有机磷组分活性增强而增加的趋势.因此,该法能用来监测土壤有机磷对植物有效性的高低.     

长期施用有机肥对土壤及不同粒级中有机磷含量与分配的影响

通过在黄棕壤上开展的 14年田间定位试验研究稻 -麦水旱轮作下长期施用有机肥对土壤及不同粒级中有机磷的影响。结果表明 :与不施肥的对照和单施化肥相比 ,有机肥与化肥长期配合施用能显著增加土壤有机磷总量 ;就有机磷的形态而言 ,长期施肥主要增加中等活性有机磷的含量。土壤不同粒级中总有机磷的含量顺序为 :0～ 2 μm >2～ 10 μm >5 0～ 10 0 μm >10～ 5 0 μm。从分配系数上看 ,土壤有机磷各形态中以对植物有效性较高的中等活性有机磷占绝对优势 ,对植物有效性最高的活性有机磷仅占 3 %左右。长期施用有机肥后使分配在活性、中等活性组分中有机磷的比例增加 ,而稳定性有机磷中的比例下降。     

Phosphorus availability and rice grain yield in a paddy soil in response to long-term fertilization

Rice (Oryza sativa L.) is one of the most important crops in the world, and its production is limited by soil phosphorus (P) deficiencies in many parts of the world. Impacts of long-term fertilization regimes on rice productivity and soil P availability is largely unknown. A long-term (26-year) field experiment in a paddy soil of southeastern China was carried out to study the response of rice grain yield and soil P pools to different fertilization regimes including control without fertilization (CK), nitrogen, P, and potassium (NPK) fertilizer (NPK), NPK fertilizer plus cattle manure (NPKM), and NPK fertilizer plus rice straw (NPKS). Application of fertilizers (NPK, NPKM, and NPKS) increased rice grain yield compared with the CK treatment (on average, by 75%, 97%, and 92%, respectively). Soil P was predominately present in the organic form (51–75% of total P) across different treatments. Most soil inorganic P fractions decreased with time due to continuous depletion by rice plants in the nonfertilized treatment (CK), while they generally increased with time in the fertilizer treatments (NPK, NPKM, and NPKS) due to continued supply of P to soil. On the other hand, soil organic P fractions increased continuously with time regardless of treatment, probably due to the retention of stubble and biological immobilization of inorganic P. Positive relationships between the rice grain yield and most inorganic P fractions in the CK treatment indicated the P limitation for rice production due to no P inputs and long-term conversion of inorganic P into organic P.     

Changes in soil nitrogen,phosphorus, and potassium under intensive cropping in sub‐humid tropics of India

Abstract

Efficient soil fertility management is essential for sustained production of high crop yields. Field experiments were conducted on an Entisol soil during 1984 to 1987 at Bidhan Chandra Agricultural University, West Bengal, India, to study the changes in soil N, P, and K in sub‐humid tropics under irrigated intensive cropping in rice‐potato‐mung bean (Oryza sativa L.‐ Solanum tuberosum L.‐ Vigna radiatus Roxb.) and rice‐potato‐sesame (O. sativa L.‐ S. tuberosum L.‐ Sesamum indicum L.) cropping sequences. The crops were grown with or without application of farmyard manure and with or without incorporation of crop residues. Different quantities of inorganic fertilizers based on locally recommended practices for fertilization were applied to rice and potato, and their residual effects on succeeding mung bean or sesame crops were assessed. At the end of experimentation, the total N status of soil improved more under the rice‐potato‐mung bean sequence than under the rice‐potato‐sesame sequence. The available phosphorus status of soil showed a positive balance in both sequences except in the treatment receiving 50% of the recommended amounts of N, P, and K. A reduction in the recommended fertilization without a compensating application of manure or crop residues resulted in the depletion of soil‐available K. All treatments reduced nonexchangeable K, and depletion was low wherever manure or crop residues were added into the cropping system. Integration of inorganic fertilizers with organic fertilizers, such as manure or crop residues, maintained soil N, P, and K under intensive agriculture and sustained soil productivity.     

Organic phosphorus speciation and pedogenesis: analysis by solution 31P nuclear magnetic resonance spectroscopy

Changes in phosphorus (P) during soil development are central to the understanding of labile P for plant productivity and soil P management. We used NaOH‐EDTA extraction with ³¹P nuclear magnetic resonance spectroscopy (³¹P NMR), sequential P fractionation, and general soil chemical characterization to better our understanding of P dynamics within two chronosequences (Manawatu and Reefton) and one Basalt maturity sequence under original native vegetation. With time, orthophosphate and orthophosphate monoesters tended to increase with organic C to a maximum of about two‐thirds of NaOH‐EDTA‐extractable P in young soils (16 000 years in the Reefton chronosequence), but gradually declined thereafter to about one‐third of NaOH‐EDTA‐extractable P in the oldest soils (130 000 years old). This coincided with a depletion of P from primary minerals (e.g. apatite) and readily available P for plant production. This depletion of inorganic P resulted in a greater reliance on organic P cycling via mineralization, hence the depletion of the normally recalcitrant monoester‐P pool. Concomitantly, the build‐up of labile P species (diesters and pyrophosphate) and scyllo‐ over myo‐inositol hexakisphosphate occurred as soils developed, and might be attributed to microbial activity, including scavenging for P. This work highlights the importance of organic P cycling during pedogenesis.     

Phosphorus forms and enzymatic hydrolyzability of organic phosphorus in soils after 30 years of organic and conventional farming

Lower P‐input levels in organic than conventional farming can decrease soil total and available P, which can potentially be resupplied from soil organic P. We studied the effect of 30 y of conventional and organic farming on soil P forms, focussing especially on organic P. Soil samples (0–20 cm) were taken in a field experiment with a nonfertilized control, two organic systems receiving P inputs as animal manure, and two conventional systems receiving only mineral P or mineral P and manure. Soils were analyzed for total, inorganic, organic, and microbial P, by sequential P fractionation and by enzyme additions to alkaline soil extracts. Samples taken prior to starting the experiment were also analyzed. Average annual P balances ranged from –20 to +5 kg ha^–1. For systems with a negative balance, labile and moderately labile inorganic P fractions decreased, while organic and stable inorganic P fractions were hardly affected. Similar quantities and proportions of organic P extracted with NaOH‐EDTA were hydrolyzed in all soils after addition of an acid phosphatase, a nuclease, and a phytase, and enzyme‐stable organic P was also similar among soils. Thus, neither sequential fractionation nor enzyme addition to alkaline soil extracts showed an effect of the type of applied P (manure vs. mineral) on organic P, suggesting that organic P from manure has largely been mineralized. Thus far, we have no indication that the greater microbial activity of the organic systems resulted in a use of stable P forms.     

生物质炭施用对杉木幼苗土壤磷组分的影响

通过盆栽试验，采用Hedley连续浸提法研究不同生物质炭施用量处理（CK：0 t/hm²；B₁₂：12 t/hm²；B₃₆：36 t/hm²）对杉木幼苗土壤磷组分的影响。结果表明：与CK相比，试验180 d后B₁₂和B₃₆处理土壤全磷与有效磷含量分别增加了8.7%~26.0%和24.0%~101.7%，有效磷在全磷中的比例显著提高；土壤磷组分中，残余态磷在全磷及无机磷组分中的比例均最高，分别为48.5%~51.1%和58.7%~68.3%。B₃₆处理下，土壤各无机磷组分均显著增加，其中易分解态磷和中等易分解态磷在无机磷中的比例显著提高，而稳定态磷和残余态磷的比例显著降低。中等易分解态磷占总有机磷的比例最高，达69.3%~70.2%，生物质炭施用对各有机磷组分在总有机磷中的比例影响均不显著，仅在B₃₆处理下，土壤有机磷中易分解态磷和中等易分解态磷含量显著降低。冗余分析表明，土壤全碳与各无机磷组分呈显著正相关关系，与有机磷组分呈显著负相关关系，是影响土壤磷组分变化的关键因子。     

Inorganic and organic phosphorus pools in earthworm casts (Glossoscolecidae) and a Brazilian rainforest Oxisol

We compared differences in soil phosphorus fractions between large earthworm casts (Family Glossoscolecidae) and surrounding soils, i.e., Oxisols in 10 year-old upland agroforestry system (AGR), pasture (PAS), and secondary forest (SEC) in the Central Brazilian Amazon. AGR and PAS both received low-input fertilization and SEC received no fertilization. We found that earthworm casts had higher levels of organic hydroxide P than surrounding soils, whereas fertilization increased inorganic hydroxide P. Inorganic P was increased by fertilization, and organic P was increased by earthworm gut passage and/or selection of ingested materials, which increased available P (sum of resin and bicarbonate fractions) and moderately available P (sum of hydroxide and dilute acid fractions), and P fertilizer application and land-use increased available P. The use of a modified sequential P fractionation produced fewer differences between earthworm casts and soils than were expected. We suggest the use of a condensed extraction procedure with three fractions (Available P, Moderately Available P, and Resistant P) that provide an ecologically based understanding of the P availability in soil. Earthworm casts were estimated to constitute 41.0, 38.2, and 26.0 kg ha⁻¹ of total available P stocks (sum of resin and bicarbonate fractions) in the agroforestry system, pasture, and secondary forest, respectively.     

长期施肥对塿土磷素状况的影响

利用塿土12年长期肥料定位试验,研究了不同施肥方式对耕层土壤全磷(TP)、有机磷(OP)与有效磷（Olsen-P）的影响。结果表明,施用化学磷肥提高了耕层土壤TP、Olsen-P含量,但并未提高OP含量;对照与磷钾处理的OP含量有降低趋势。当基于含氮量施有机肥时,土壤TP和Olsen-P含量大幅度提高,也提高了OP含量,但OP/TP比率在降低到一定程度后维持在一个较为稳定的水平;即使施用有机肥的处理,磷素也主要以无机形态累积。土壤Olsen-P与TP或两者的增加量都呈显著的线性相关,塿土TP每提高100 mg/kg,Olsen-P增加量约为20.8 mg/kg,且单位土壤全磷增加带来的Olsen-P增加有随施肥时间降低的趋势。在土壤Olsen-P含量达到一定水平时应考虑减少磷肥用量。基于有机肥中磷素含量来推荐有机肥施用或延长其施用的时间间隔,将有助于减少由于有机肥施用带来的磷素大量快速累积。     

长期施肥对栗褐土有机碳矿化的影响

【目的】 土壤有机碳矿化是土壤中重要的生物化学过程,与土壤养分的释放、土壤质量的保持以及温室气体的形成密切相关。本文以 25 年长期定位施肥试验为依托,对栗褐土土壤有机碳矿化速率、有机碳累积矿化量的动态变化进行研究,为科学管理土壤肥力、增加栗褐土碳汇、减少温室气体排放提供依据。 【方法】 田间试验开始于 1988,共设置 8 个施肥处理:不施肥 (CK);单施氮肥 (N);氮磷肥合施 (NP);单施低量有机肥(M₁);低量有机肥与氮肥合施 (M₁N);低量有机肥与氮磷肥合施(M₁NP);高量有机肥与氮肥合施 (M₂N);高量有机肥与氮磷肥合施 (M₂NP)。于 2013 年玉米播种前,采集耕层 (0—20 cm) 土壤样品,采用室内培养方法,对土壤碳矿化释放 CO₂ 的数量和速率进行测定,并利用一级动力学方程计算出土壤有机碳库潜在矿化势和周转速率。 【结果】 各肥料处理不同程度地提高了栗褐土总有机碳含量,以高量有机肥与化肥配施作用最为显著。与 CK 相比,M₂N、M₂NP 处理土壤总有机碳含量增加了 121.1%、166.8%。不同处理土壤样品培养有机碳矿化速率均在第一天达到峰值,随后急剧下降。5 d 后,下降趋缓,不同处理 CO₂ 产生速率趋于一致。培养期间,各处理矿化速率变化符合对数函数关系。长期施用不同肥料均可以提高栗褐土有机碳的矿化速率,其大小顺序为:有机肥与化肥配施 > 单施有机肥 > 单施化肥 > 对照。培养 57 d 后,各处理土壤有机碳累积矿化量为 555.0～980.3 mg/kg,以 M₂NP、M₁N 的累积量较高,为对照的 1.77 倍、1.73 倍。长期施肥栗褐土有机碳矿化率呈下降趋势,以处理 M₂NP 下降最明显,与对照相比,降低了 6.3 个百分点。施肥处理土壤的潜在矿化势均高于对照,M₁N、M₂NP 最高,为 923.7 mg/kg 和 926.4 mg/kg,较对照增加了 74.0% 和 74.5%。不同施肥处理均可明显提升土壤有机碳的周转速率,减少周转时间,其中处理 M₁NP、M₂NP 效果最为明显。 【结论】 长期施用化肥、有机肥及有机无机肥配施可有效促进栗褐土有机碳的积累,提高有机碳的矿化速率和周转速率,降低有机碳的矿化率 (累积矿化量占有机碳总量的比率),加强了土壤的固碳能力,以 M₂NP 处理的效果更佳。      

Phosphorus characterization of manure composts and combined organic fertilizers by a sequential‐fractionation method

Characterization of the forms of phosphorus (P) in organic soil amendments was conducted by sequential P fractionation. More than 60% of total P was inorganic P (P_i). The major P_i forms in the cattle‐manure composts were NaHCO₃‐ and HCl‐extractable P fractions. HCl‐extractable P_i was the predominant P form and a considerable proportion of the total P was present in the HCl‐extractable organic P fraction in the poultry manure composts and combined organic fertilizers.